Two-temperature refrigerating system



Patented July 29, 1952 TWO-TEMPERATURE REFRIGERATING SYSTEM Leonard W.Atchison, Erie, Pa., assignor to General Electric Company, a.corporation of New York Application April 21, 1949, Serial No. 88,708

My invention relates to refrigerating systems and more particularly torefrigerating systems including a plurality of evaporators.

In many refrigerating systems it is desirable to employ a plurality ofevaporators. For example, in combination refrigerators, which include acompartment for storing frozen food and a second compartment for storingfresh food, it may be necessary to provide two evaporators, one of whichoperates at a low temperaturefor refrigerating the frozen foodcompartment, and the other of which operates at a higher temperature forrefrigerating the fresh food compartment. Where both evaporators aresupplied with refrigerant from a common condensing unit, somearrangement may be utilized for selectively directing liquid refrigerantto one or the other of the evaporators. Also, it may be desirable insome instances to operate the higher temperature evaporator on adefrosting cycle so that any frost accumulated during the operatingperiod of the higher temperature evaporator is melted and disposed ofduring the idle period of this evaporator.

Accordingly, it is an object of my invention to provide a refrigeratingsystem including two evaporators and including an improved arrangementfor directing refrigerant selectively to either evaporator.v

It is another object of my invention to provide an improvedrefrigerating system. including two evaporators operated at differenttemperatures and including an arrangement for making a substantial bodyof liquid refrigerant available to the higher temperature evaporatorwhen refrigeration is called for by the higher temperature evaporator.

Further objects and advantages of my invention will become apparent asthe following description proceeds and the.features of novelty which.characterize my invention will be pointed outwith particularlity in theclaims annexed to. and forming; part of this specification.

In carrying out my invention a refrigerating system. is provided. whichincludes two. evaporators. A reservoir is provided for receiving 1liquid refrigerant from the condensing. unit and discharging therefrigerant selectively to either evaporator. Where the two evaporatorsare operated at different temperatures, the conduits connecting the twoevaporators to the reservoir are arranged so that a substantial body ofliquid refrigerant is maintained in the reservoir during refrigerationof the low temperature evaporator and this refrigerant is immediatelyavail- 13 Claims. (01. 52-3) able for discharge to the highertemperature evaporator when that evaporator calls forrefrigeration. Thevaporization of this body of liq'uid refrigerant in the highertemperature evaporator effects a rapid increase in the suction pressureof the system and hence the system rapidly reaches a more eflicientoperating condition. during the time when refrigeration is supplied tothe higher temperature evaporator. 4 A

For a better understanding of my invention reference may be had to theaccompanyingdrawing in which Fig. l is a schematic illustration of avrefrigerating system incorporating; my: invention; Fig. 2 shows aportion of the apparatus illustrated in Fig; 1 in a differentpositionyand Fig. 3 shows a modified form of a portionoftherefrigerating system; and Fig. 4 is a schematic illustration of amodified form of my invention.

Referring now to Figs. 1 and 2, there is illustrated a refrigeratingsystem including a condensing unit I and two evaporators 2" and}. Thecondensing unit includes .a motor-compressor unit'positioned within. ahermetically-sealed case 4 and. a, condenser 5. Liquid refrigerant. issupplied from the condenser 5 through a restricted conduit, or capillarytube, 6.

In order to direct liquid refrigerant from:the condensing" unitselectively to either of the two evaporators. 2 and 3, an elongatedreservoir lis provided. The conduit 6 is connected to' :the reservoir Iat. the top central. portionthereofias indicated at 8. Refrigerantissupplied from: the reservoir 1 to the evaporator. 2 through. a: conduit9, and refrigerant is similarly supplied. to'the evaporator 3v through aconduit ll]. As implied above, the term reservoir as used: in. thisspeci- 'fication and. the claims thereof is. intended. to

denote a storage container of appreciable size capable of storing asubstantial body of refrigerant, and specifically capable of" storingsuflicient liquid refrigerant to havea materialxeffect in rapidlyraising the pressure of the higherutemperature evaporator whenthisrefrigerant is discharged thereto. The specific manner' invwhichthis is carried out. in the applicants: invention is pointed out indetail in-this: specification.

A common header II' is provided for the 'two evaporators 2 and 3'. Theevaporator *Z i's connected to one end of the header: H by a conduit 12,the evaporator 3 is connected to the same end of the header by a conduit13, these conduits primarily conducting vaporized refrigerant from theevaporators to the header. Vaporized refrigerant is discharged from the.header to the condensing unit I through a suction line I4 In order tominimize discharge of liquid refrigerant from the header I I to thecompressor of the condensing unit I, a baffle I5 is provided within theheader I I. To prevent reverse flow of refrigerant from the header I Ito the evaporator 2 when the evaporator 3 is operating, a check valve I6is provided in the conduit I2 between the evaporator 2 and the header II.

In one application of this refrigerating system the evaporator 2 isoperated at a low temperature, such as would be required forrefrigerating a frozen food storage compartment, and the evaporator 3 isoperated at a higher temperature,

1 such as would be required for refrigerating a fresh food storagecompartment. By way of example, the evaporator 2 may be operated at atemperature in the neighborhood of 0 F., and the evaporator 3 may beoperated over a temperature range from a minimum of 28 F. to a maximumof 35 F. The reservoir I is arranged to direct liquidrefrigerant fromthe condensing "unit. .to either the low'temperature evaporator 2 or thehigher temperature evaporator 3. To accomplish this the reservoir I ispivotally supported at I! for movement "from the position shownin Fig. 1tothe position shown in Fig, 2. In order to allow for-the above movementof the reservoir the conduits 6, 9, and IB-include flexible coiledportions I8, I 9, and 20, respectively. It

can be seen that when the reservoir occupies the position shown in Fig.1, liquid refrigerant-is directed through the conduit 9 to the lowtemperature evaporator. 2. When the reservoir is tilted to the positionshown in Fig. 2 liquid refrigerant is dircted'through the'conduit ID tothe higher temperature evaporator 3.

" It'canbe seenby reference to Figs. 1 and 2 that when the reservoir '1occupies the position shown in Fig. 1; liquid refrigerant is suppliedthrough the conduit 9 and any flash vapor'in the reservoir I is passedthrough the conduit, I9 and the evaporator 3; when the reservoir'is inthe position shown in Fig. 2, liquid refrigerant is'sup- 'plied to theevaporator 3 through the conduitIO and flash vapor passes through theconduit 9 and the evaporator 2. Thediameter and length of the conduits 9and ID are chosen so that the pressure drop due to the flow of flashvapor through one conduit'is somewhat greaterv than the pressure dropdue to the flow of liquid through the other.

Particularly, when the'liquid refrigerant is being supplied to theevaporator 3, it is im- 'portant that the resistance to passage of flash"vapor through the conduit 9 be greater than the resistance to thepassage of liquid through the conduit I0, since the evaporator 2'operates at a somewhat lower temperature and pressure than theevaporator 3. I

r Axtension spring -2I' is connected to the free end of the reservoir Iat 22-for normally biasing the'reservoir to the position shownin Fig. 1.In orderto shift the reservoir to; the position shown in-Fig. 2 whenrefrigeration is required by the higher temperature'evaporator 3, asolenoid 23 is'provided. This solenoid actuates an armature 24, which ishinged at 25 .to the reservoir, to move the reservoir to the positionshown in Fig. 2.

evaporator 3 reaches a predetermined maximum temperature which causes anexpansion of the bellows 28 to close the contacts 29, the solenoid 23 isenergized and moves the reservoir I to the position shown in Fig. 2 todirect liquid refrigerant from the reservoir to the evapoator 3.

The operation of the motor-compressor unit within the case i iscontrolled bya temperatureresponsive bulb 32 which is positioned incontact with the low temperature evaporator 2. The bulb 32 is connectedby a tube 33 to a bellows 34. The" expansion and contraction of thebellows closes and opens a circuit from the power lines 30, ii throughcontacts 35 to the motor of the motorcompressor unit. Hence, when thetemperature of the evaporator 2 reaches a predetermined maximum theexpansion of the bellows 34 under the control of thetemperature-responsive bulb 32 closes the circuit to the motor to startoperation of the condensing unit. Conversely, when the temperature ofthe evaporator 2 reaches a predetermined minimum, the circuit of themotor is interrupted to stop the operation of the condensing unit.

In order to operate the systemgmore efficiently, it is desirable to havea higher suction pressure during the time when the higher temperatureevaporator is being refrigerated. Should the condensing apparatuswithdraw refrigerant from the higher temperature evaporator at the samelow pressure as is utilized for operating the low temperature evaporator2, there would be a considerable sacrifice in emciency. In order toraise the suction pressure rapidlywhen refrigeration is shifted to thehigher temperature evaporator 3, a particular arrangement of theconduits 9 and ID with respect to the reservoir 1 is provided. Thus, theconduit 9, which supplies liquid refrig" erant from the reservoir to thelow temperature evaporator 2,is connected to the reservoir in the upperportion of one end. It can be seen by referring to Fig. 1 that thisarrangement of the conduit 9 in communication with the reservoir 1causes a substantial body of liquid refrigerant 36 to be retained withinthe reservoir during refrigeration of the low temperature evaporator. 0nthe other hand, the conduit I0, through which liquid refrigerant issuplied from the reservoir. T to the evaporator 3, is connected to thereservoir in the lower portion thereof at the opposite end from theconduit 9. Therefore, when the reservoir is tilted to the position shownin Fig. 2, the body of liquid refrigerant 35 immediately becomesavailable for discharge to the higher temperature evaporator 3. Thevaporization of this substantial body of liquid refrigerant in theevaporator 3 causes a rapid increase in the suction pressure and hencethe system rapidly begins operation at the more efficient higherpressure. In the absence of the arrangement described above there wouldat best be a delay in achieving an increased suction pressure during therefrigeration by evaporator 3, and hence there would be an unnecessarilylow efficiency at least during this period of delay.

In order to avoid the necessity of defrosting the fresh food evaporator3. it may be desirable to operate this evaporator on a defrosting cycle.To accomplish this, the evaporator 3 may be operated over a temperaturerange above and below the freezing point of water such that any frostcollecting during the time that the evaporator 3 is refrigerating ismelted and dissipated during the time that the evaporator 3 is notrefrigerating. For example, this evaporator might "beoperatedoveralrange of temperatures from'a minimum of 28 F to a maximum oft 5.In Fig. 3 there ;is shown a modifiedrf-ormof a .portion ofthetrefrigeratingxsystem in which a rearrangement of the connectionof "theconduit 12 to .the header H is utilized to eliminate the check valve It.lEn this modification the conduit :2 isconnected in communication withthe header 'H .at the bottom portion. thereof :sothat the :mouth 3'! of:the conduit 12 isiocatedhelow the level .38 .ofiliquidirefrigerantnormally presentin theheader I l. Liquidtrefrigerant isz-forced from theheader H :into -the evaporatortZ, but

since there is no pressure difference between the two evaporators in theform shown in Fig. :3.

The operation of the refrigerating systeinmay be summarized as follows.When the low temperature evaporator :2 reaches a predetermined maximumtemperature, the condensing unit is started in operation by the. closingof the contacts 35. Liquid refrigerant is supplied through the capillarytube '6 to the reservoir'l. The reservoir I is normally-biased by thespring 2! to the tilted position shown in Fig. 1. Hence, assuming theevaporator 3 is below its predetermined maximum temperature, liquidrefrigerant is supplied through the conduit 9 to the low temperatureevaporator 2.

reservoir because of "the positioning of the con- 'd'uit S incommunication with the reservoir at the upper portion of one end. Shouldthe higher temperature evaporator 3 mined maximum temperature, thesolenoid 23 is energized by the closing of the contacts '29 and thereservoir is tilted to the position shown in Fig. 2. In this positionliquid refrigerant is supplied to the higher temperature evaporator 3.Also, the substantial body of liquid refrigerant 36 retained in thereservoir during "the operation of the low temperature evaporator 2 isimmediately made available for the higher temperature evaporator 3 andis enabled to discharge to that evaporator because of the positioning ofthe conduit :0 in communication with the reser voir l at the lowerportion o'f the reservoir. This supplying of a substantial 'bodyofliquidrefrigerant to the higher temperature evaporator 3 results in arapid increase in the suction line pressure because of the vaporizationof this refrigerant, and hence the refrigerating system rapidly beginsto operate at a higher-efiiciency. During the operation of the highertemperature evaporator 3 vaporized refrigerant is prevented from backingup into the evaporatori through the conduit l2 either by the use of thecheck valve i6 or by connecting the conduit I2 to the header H beneaththe normal level-of the liquid refrigerant therein.

In the modification shown in Fig. 4a solenoid valve arrangement isutilized in lieu 'of the tilting reservoir for selectively directingliquid refrigerant either to the low temperature evaporator 2 or to thehigher temperature evaporator 3. The same numerals have-been used todesignate corresponding parts in Figs. 1 and 4. Referring to Fig. 4,there is shown a solenoid-operated valve 39 whichin'oludes-a housing 40..A partition 4| During this time a. body of liquid refrigerant 36 isretained in the reach its prede'terl conduit 16.. 'rected from thehousing :41] either through the -:is"formedwithin the housing and thispartition includes a valve seat 42 against which onewen'd -P5.3..0f2.2'd011b16-6I1d6d valve element. may :be seated. .The housing 4!]further includes a sec- :ond valve seat "4'5 against which the other end46 :of the td-ouble-ended'valve element 44 is adapted to seat. Liquidrefrigerant is supplied to the housing 49 from the condensing -;unitthrough a ,"Liquidrefrigerant .is selectively dicondu'it 9 :to the .lowtemperature evaporator 2 or through thexconduit 10 to the :highertemperature evaporator 13.

?T0 cnntrol theiflow of refrigerant to the evaporators .2..and 31117118valve element M is provided, and this :valve element is operated by asolenoid 41.

Whenthe ssolenoid x4! is energized it acts upon an armature 48 to liftthe valve element 44 tosthe'position shown in Fig. 4 wherein liquidrefrigerant is supplied through the conduit it to the evaporator 3 andflow of liquid refrigerant to the evaporatorZ isblockedby the engagementof :the .end 43 of the valve element 44 with the seat 42. When thesolenoid 4! is deenergized, the valve element 44 falls by gravity intoengagement with the seat 45 to block the'ilow of liquid refrigerant tothe evaporatorS and at the same time to disengage the valve element fromthe seat 42 directing the refrigerant through the conduit 9 to theevaporator 2. The housing ti], or at least :a portion thereof adjacentthesolenoid 4'! .and the armature t8, is made of a nonmagnetic material.

As in the form previously described, a temperature-responsive bulb at isprovided in contact with the evaporator'fi and this bulb is 'connectedby the tube Z'l to the bellows 28. When the evaporator 3 reaches apredetermined maximum temperature, the bellows 28 expands to close thecircuit to :the solenoid from the power lines 3i}; 3! through thecontacts 29. This causes the lifting. of the valve element '54 to theposition shown .inFig. 4 and the supplying of liquid refrigerant tothehigher temperature evaporator 3. When the evaporator .3 reaches apredetermined minimum temperature the circuit of the solenoid isinterrupted by the contraction of the bellows 12:8 and the valve element44 falls by gravity :into engagement with the valve seat 45,

blocking the flow of refrigerant to the higher temperature evaporator 3and opening a path for flow of refrigerant past the valve seat andthrough the conduit 9 to the low temperature evaporator 2. The-starting.and stoppingof the motor compressor .unit .(not shown) may be controlledby a bulb "responsive to the temperature of the evaporator 2, as;in theform shown in Figs. 1 and 2.

inorder to make a body of liquid refrigerant available for discharge tothe higher temperatureevaporatoras soonas the higher temperatureevaporator calls for refrigeration, so that the system 'refrigerates thehigher temperature evaporator at a higher efficiency, the housing 40includes a reservoir 49 .at the lower portionthereof. "The conduit-1 5!is connected in communication with the reservoir ltil at the bottom ofthis reservoir. On the other hand, the conduit 9, through which liquidrefrigerant 'is supplied to the low temperature evaporator, ispositioned in c'ommunicationrwith the housing i!!- at the top of thereservoir. 49. It can be seen that when the valve elementsll is in itslower position the liquid refrigerant in the housing'dii must rise inthe reservoir 49 to the level of the conduit 9 before liquid refrigerantcan be supplied at the low temperature evaporator 2. Thus, a substantialbody-of liquid refrigerant is maintained in the reservoir t9 while thelow temperature evaporator is being refrigerated. When the highertemperature evaporator calls for refrigeration and hence when the valveelement 44 is shifted to the position shown in Fig. 4, this body ofliquid refrigerant within the reservoir 49 is immediately made availablefor discharge to the higher temperature evaporator 3. The vaporizationof this substantial body of liquid refrigerant in the evaporator 3causes a rapid increase in the suction pressure and hence the systemrapidly begins to operate at the increased efficiency resulting fromoperation at a higher suction pressure, in the same manner as previouslydescribed in connection with Figs. 1 and 2.

While I have shown and described specific embodiments of my invention, Ido not desire my invention to be limited to the particular constructionsshown and described, and I intend by the appended claims to cover allmodifications within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A refrigerating system comprising a condensing unit, a lowtemperature evaporator, a higher temperature evaporator and a tiltablereservoir connected in a closed refrigerant circuit, means forconducting liquid refrigerant from said condensing unit to saidreservoir, means connected to the upper portion of said reservoir forconducting liquid refrigerant from said reservoir to said lowtemperature evaporator, and means connected to the lower portion of saidreservoir for conducting liquid refrigerant from said reservoir to saidhigher tem perature evaporator, said reservoir being tilted in onedirection for directing liquid refrigerant from said reservoir to saidlow temperature evaporator, sad reservoir being tilted in the oppositedirection for directing liquid refrigenant from said reservoir to saidhigher temperature evaporator, said connecting means providing forretention of a substantial body of refrigerant in said reservoir whensaid reservoir is tilted in said one direction and making saidsubstantial body of liquid refrigerant immediately avai1- able to saidhigher temperature evaporator when said reservoir is tilted in saidopposite direction.

2. A refrigerating system comprising a condensing unit, a lowtemperature evaporator, a

higher temperature evaporator and a reservoir connected in a closedrefrigerant circuit, means for conducting liquid refrigerant from saidcondensing unit to said reservoir, means for directing liquidrefrigerant from said reservoir selectively to either of saidevaporators, means communicating with the upper portion of saidreservoir for conducting liquid refrigerant to said low temperatureevaporator, said communicating means being effective to retain asubstantial body of liquid refrigerant in said reservoir when saiddirecting means directs refrigerant to said low temperature evaporator,and means communicating with the lower portion of said reservoir forconducting liquid refrigerant to said higher temperature evaporatorwhereby said substantial body of liquid refrigerant retained in saidreservoir during refrigeration of said low temperature evaporator isimmediately made available for said higher temperature evaporator whensaid directing means directs liquid refrigerant to said highertemperature evaporator.

3. A refrigerating system comprising a condensing unit, a lowtemperature evaporator, a higher temperature evaporator and a reservoirconnected in a closed refrigerant circuit, means for conducting liquidrefrigerant from said condensing unit to said reservoir, asolenoid-operated valve for directing liquid refrigerant from saidreservoir selectively to either of said evaporators, means communicatingwith the upper portion of said reservoir for conducting liquidrefrigerant to said low temperature evaporator, means communicating withthe lower portion of said reservoir for conducting liquid refrigerant tosaid higher temperature evaporator whereby liquid refrigerant retainedin said refrigerant during refrigeration of said low temperatureevaporator is immediately made available to said higher temperatureevaporator when said valve directs liquid refrigerant to said highertemperature evaporator.

4. A refrigerating system comprising a condensing unit, a lowtemperature evaporator, a higher temperature evaporator and a valveconnected in a closed refrigerant circuit, said valve including ahousing having a reservoir for liquid refrigerant therein, means forconducting liquid refrigerant from said condensing unit to saidreservoir, said valve being normally biased to one position fordirecting liquid refrigerant from said reservoir to said low temperatureevaporator, a solenoid positioned-adjacent said valve, means responsiveto a condition of said higher temperature evaporator for energizing saidsolenoid to shift said valve to a second position for directing liquidrefrigerant from said reservoir to said higher temperature evaporator,means communicating with the upper portion of said reservoir forconducting liquid refrigerant to said low temperature evaporator wherebya substantial body of liquid refrigerant is retained in said reservoirduring operation of said low temperature evaporator, and meanscommunicating with the lower portion of said reservoir for conductingliquid refrigerant from said reservoir to said higher tem peratureevaporator whereby said substantial body of liquid refrigerant isimmediately made available to said higher temperature evaporator whensaid valve is shifted to said second position to direct liquidrefrigerant to said higher temperature evaporator.

5. A refrigerating system comprising a condensing unit, two evapcratorsand a tiltable reservoir connected in a closed refrigerating circuit,means for conducting liquid refrigerant from said condensing unit tosaid reservoir, means for conducting liquid refrigerant from saidreservoir to said evaporators, means normally biasing said reservoir inone direction for directing liquid refrigerant to one of saidevaporators, and means for tilting said reservoir in the oppositedirection for directing liquid refrigerant to the other of saidevaporators.

6. A refrigerating system comprising a condensing unit, a lowtemperature evaporator, a higher temperature evaporator and a tiltablereservoir connected in a closed refrigerant circuit, means forconducting liquid refrigerant from'said condensing unit to saidreservoir, means for ccnducting liquid refrigerant from said reservoirto said evaporators, means normally biasing said reservoir in onedirection for directing liquid refrigerant from said reservoir to saidlow temperature evaporator, and means for tilting said reservoir "in theopposite direction for direct in'gfliqu'id-refrigerant from saidreservoir to said higher temperature evaporator, I

7. A refrigerating system'pompnsing a con densing unit, a low temprature evaporator, a higher temperature evaperatoranu a tiltablereservoir connected in a closed refrigerant circuit, means forconducting liquid ref-rige'rantfrom said condensing i'ihit to-saidreservoir, means for conducting liquid refrigerant from said reservoirt's said eva erators; means normally biasing said reservoir in onedirection'for directing liquidrefrige'rant' i r orn said reservoirtosaidlow' temperature evaporator, and a solenoid energized .in responseto a condition of-saidhig'he'r temperature evaporator for tilting saidreservoir in the: opposite dire'ction to direct liquid refrigerantfroinsaid reservoir to said higher temperature evaporator.

8; A refrigerating system comprisingacondensiiig unit ia.lowtemperatdrie -evapo; .ator,,.,a higher temperature evaporator.ltiltable res'er voir,v connected in a closed. refrigerant. circuit,means for conducting liquid refrigerant from said condensing. unit ,to.said reservoir, a common header for said evaporat-ors, a suction linefor conducting vaporized refrigerantfrom said header to saidcondensing.unit, a checkvalve for blocking reverse flow of refrigerant from saidheader to said low temperature evaporator, means normally biasing saidreservoir inone direction for directingliquid refrigerant; from saidreservoir to said low temperature evaporator, and a,:s o lenoidenergized in response to a condition of :said h h r; t mp a ure .evap raoa tiaa sa d reservoir in the opposite direction to direct liquidrefrigerant from said reservoir to said higher temperature evaporator.

9. A refrigerating system comprising a condensing unit, a lowtemperature evaporator, a higher temperature evaporator and a tiltablereservoir connected in a closed refrigerant circuit, means forconducting liquid refrigerant from said condensing unit to saidreservoir, a common header for said evaporators, a suction line forconducting vaporized refrigerant from said header to said condensingunit, a conduit for connecting said low temperature evaporator incommunication with said header, said conduit being connected to saidheader beneath the normal level of liquid refrigerant therein wherebyflow of vaporized refrigerant from said higher temperature evaporatorthrough said header to said low temperature evaporator is blocked, meansnormally biasing said reservoir in one direction for directing liquidrefrigerant from said reservoir to said low temperature evaporator, anda solenoid energized in response to a condition of said highertemperature evaporator for tilting said reservoir in theoppositedirection to direct liquid refrigerant from said reservoir to saidhigher temperature evaporator.

10. A refrigerating system comprising a condensing unit, a lowtemperature evaporator, a higher temperature evaporator and an elongatedreservoir connected in a closed refrigerant circuit, said reservoirbeing pivotally mounted for tilting movement to direct liquidrefrigerant to one end or the other of said elongated reservoir, aconduit for conducting liquid refrigerant from said condensing unit tosaid reservoir, a second conduit communicating with said reservoir forconducting liquid refrigerant to said low temperature evaporator, saidsecond conduit being connected to the upper portion of said reservoir atone end thereof, a third conduit communicatconnected to the lowerportion of said reservoir at the opposite end thereof, means-for tilting said reservoir in one direction to direct liquid ife-- rrr eranrrromsaiureservuir 'tofsaid low tempera sure evaporator,the-'connectin'g-pf- "said secondconduit to the" up er portie'n of sa'idre'servoir eau g a-substantial body of liquid refrigerant to be retainedin said reservoir when said reser voi'r is tuted insaiu one direction,and-means for tiltin'g said reservoir i'n t'h'e opposite 'ec'tio directliquid refrigerant from saidreservoir to' saicl higher-temperatiireevaporatofisaid substanti'al body or liquid refrigerant being iiir'imediately made; available to :said highertemperatureevaporatoropposite-xiii ction'." a y 11 n refrigerating system comprising "amendensing unit; a low temperature evaporatorp'a higher temperature"evaporator and an elongated reservoir connected in iaelosed refrigerant(Eir cult, said reservoir lfleing' piv'otally mounted for tiltingmovement to direct liquid re'frigrant to one :end or the otherbf *saidelon-gat" d reservoir, a conduit :rereoudue'tiug liquid refri era-ntrrom said-condensing unit to said reservoir, a second conduitcommunicating with said reservoir for conducting "liquid refrigerantsaid iew: t "nipierature evaporator, said seconds duitconnected to theupper portion of said reservoir at one end thereof, a'thiid conduitcommunieatingwith said :r'es'e v'oirfor conducting liquidrefrigerantfrom said reservoir. to said -ihi'gheh temperature evaporator, saidthird conduit being connected to the lower portion of said reservoir atthe opposite end thereof, means normally biasing said reservoir in onedirection to direct liquid refrigerant from said reservoir to said lowtemperature evaporator, the connecting of said second conduit to theupper portion of said reservoir causing a substantial body of liquidrefrigerant to be retained in said reservoir when said reservoir istilted in said one direction, and a. solenoid energized in response to acondition of said higher temperature evaporator for tilting saidreservoir in the opposite direction to direct liquid refrigerant fromsaid reservoir to said higher temperature evaporator, said substantialbody of liquid refrigerant being immediately made available to saidhigher temperature evaporator when said reservoir is tilted in saidopposite direction.

12. A refrigerating system comprising a condensing unit, a lowtemperature evaporator, a higher temperature evaporator and an elongatedreservoir connected in a closed refrigerant circuit, said reservoirbeing pivotally mounted for tilting movement to direct liquidrefrigerant to one end or the other of said elongated reservoir, a.conduit for conducting liquid refrigerant from said condensing unit tosaid reservoir, a second conduit communicating with said reservoir forconducting liquid refrigerant to said low temperature evaporator, saidsecond conduit being connected to the upper portion of said reservoir atone end thereof, a third conduit communicating with said reservoir forconducting liquid refrigerant from said reservoir to said highertemperature evaporator, said third conduit being connected to the lowerportion of said reservoir to the opposite end thereof, a spring fortilting said reservoir in one direction to directliquid refrigerant fromsaid reservoir to said low temhen said reservoir is ti-lted' -iifsai'd"perature evaporator, the connecting of said second conduit in the upperportion of said reservoir causing a substantial body of liquidrefrigerant to be retained in said reservoir when said reservoir istilted in said one direction, and a solenoid energized in response to acondition of said higher temperature evaporator for tilting saidreservoir in the opposite direction to direct liquid refrigerant fromsaid reservoir to said higher temperature evaporator, said substantialbody of liquid refrigerant being immediatels made available to saidhigher temperature evaporator when said reservoir is tilted in saidopposite direction.

13. A refrigerating system comprising a condensing unit, a lowtemperature evaporator, a higher temperature evaporator and an elongatedreservoir connected in a closed refrigerant circuit, said reservoirbeing pivotally mounted for tilting movement to direct liquidrefrigerant to one end or the other of said elongated reservoir, aconduit for conducting liquid refrigerant from said condensing unit tosaid reservoir, 2. second conduit communicating with said reservoir forconducting liquid refrigerant to said low temperature evaporator, saidsecond conduitbeing connected to the upper portion of said reservoir atone end thereof, a third conduit communicating with said reservoir forconducting liquid refrigerant from said reservoir to said highertemperatureevaporator, said third conduit being connected to the lowerportion of said reservoir at the opposite end thereof, a common headerfor said evaporators, a suction line for-conducting vaporizedrefrigerant from said header to 12 said condensing unit, a check valvefor blocking reverse flow of refrigerant from said header to said lowtemperature evaporator, means for tilting said reservoir in onedirection to direct liquid refrigerant from said reservoir to said lowtemperature evaporator, the connecting of said second conduit in theupper portion of said reservoir causing a substantial body of liquidrefrigerant to be retained in said reservoir when said reservoir istilted in said one direction, and means for tilting said reservoir inthe opposite direction to direct liquid refrigerant from said reservoirto said higher temperature evaporator, said substantial body of liquidrefrigerant being immediately made available to said higher temperatureevaporator when said reservoir is tilted in said opposite directionwhereby vaporization of said substantial body of liquid refrigerantrapdly raises the pressure of the vaporized refrigerant in said headerand said suction line so that a more efficient operation of saidrefrigerating system is effected during refrigeration of said highertemperature evaporator.

LEONARD V7. ATCHISON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,133,948 Buchanan Oct. 25, 19382,133,949 Buchanan Oct. 25, 1938 2,242,814 Coons May 20, 1941 2,250,971Smellie July 29, 1941

